Fuel burner system



June 29, 1943.

J. A. DEUBEL FUEL BURNER 'SYSTEM Filed June 22, 1940 INVENTOR.

Jus m HDeubEZ BY I m lTTORNEY.

Patented June 29, 1943 FUEL BURNER SYSTEM Justin A. Deubel. Milwaukee, Wis., assignor to Paris: (h poration. Milwaukee, Win, a corporation ofWisoonsin Application June 22, 1940, Serial No. 341,803

"Claims.

Theinventionreiatesgenerallytooilbiu'ning systems. and more particularly to automatically controlled systems of this character having means whereby safety in automatic starting and running of such systems is assured.

Where an oil fired fuel burner is used, as for example, in a domestic heating plant, the fuel feed is normally controlled by a roomthermostat to start the burner when low temperature is sensed by the thermostat, and to stop the burner and thereby completely extinguish the time when the thermostat senses the presence of the desired temperature. since continued feeding of fuel to the burner in the absence of combustion would result in dangerous accumulation of fuel in the combustion chamber, it is essential to provide safety means in dominating controlling relation to the burner whereby abnormal combustion conditions, and particularly failure of combustion in the starting or running of the burner, will result in disabling the burner operating and controlling means in such a manus: a to prevent further feeding and accumulation of fuel. Such safety measures usually include a safety lockout switch which is opened and latched in open position when failure of combustion is sensed and prevents further operation of the burner until the look-out switch has been manually re-set by the householder or attendant.

The primary object of the present invention is to provide a new and improved oil burner system wherein simplicity and reliability are attained in all of the component elements and in wh ch safety of operation of the oil burner is assured.

Another important object is to provide a new and improved oil burner system wherein a safety lock-out switch tending constantly to assume its lock-out or safety position is retained in its closed position by the successive restraining action of a plurality of shiftable mechanical abutment devices which in normal starting, running and stopping of the burner are shifted in a predetermined normal sequence which maintains the look-out switch in its closed pomtion, and which in an abnormal functioning of the burner are shifted in a d fferent sequence which results in the release and lock-out of the safety switch.

Another object is to provide an oil burner system wherein a constant burner starting period is attained regardless of combustion conditions.

A further object is to provide a new and improved oil burner system in which thesensing of a flame failure during a normal running period of the burner results in immediate shut-down of period, a temporary power failure produces restarting upon return of power, while a flame failure during such a normal running period results in an immediate shut down and lock-out of the system.

A further and more specific object is to provide such a new and improved burner control system wherein'a thermostatic timer, which determines the length of the burner starting cycle, starts cooling immediately after the completion of the burner starting cycle and is latched in an ineffective position during continuance of normal combustion, thereby to condition the timer for immediate timing operation after a temporary power failure.

A further object is to provide a new and improved oil burner system'in which a single safety control lock-out switch is, during normal operation of the burner, controlled and held in its closed position solely in response to combustion conditions by means of such a character as to insure prompt lock-out operation of the switch in the event of flame failure.

Other objects and advantage reside in certain features of construction, circuit arrangement and operation of the various parts and arrangements which will hereinafter be more fully described in the specification and particularly pointed out in the appended claims, and of which two altemative embodiments are illustrated in the accompanying drawing.

In the drawing:

Fig. 1 is a schematic view illustrating an oilbumer system embodying the features of the invention.

Fig. 2 is a fragmental. schematic view illustrating an alternative embodiment of the invention.

While I have illustrated in the drawing and will hereinafter describe in detail but two embodimentsof the invention, it is to be understood that various changes and alternative constructions and circuits may be made by those skilled in the art without departing from the spirit and scope of the invention as defined by the appended c aims.

l1, to one side of the motor II, and the other line voltage lead ill to the other side of the motor by means including a, relay switch 23, the energizing coil 2| of the relay being governed by a low voltage circuit which includes and is controlled by the room thermostat l4. As herein shown, the relay coil 2| is constantly connected across the line wires l1 and it by a circuit comprising a wire 22. the coil 2|, a wire 23, the primary 24 of a transformer 23. and a wire 26, all in series, the secondary 21 of the transformer 23 normally acting in its o en circuit relation as a choke which prevents appreciable flow of current through relav c il 2|. when the thermostat i4 calls for heat. it closes a circuit through the secondary 21 of the transformer with the result that the relay is actuated and the burner control switch 24 is clo ed so as to start the burner.

The present invention is herein shown as embodi d in an oil burner system of the constant ignition ty e. it being understood, of course. that those skilled in the art could readily modify the illustrated system to provide for intermittent i nition. Where such constant ignition is to be empl yed. the ignition means I 3 is connected in paral el across the motor so as to be controlled by the motor circuit. The motor control circuit from the motor H to the line voltage lead Ill includes a wire 23 to one terminal of the relav switch 20. and a wire 23 from the other terminal of the relay switch 23 to one terminal of the safety lock-out switch I3, the other terminal oi. which is connected to the line voltage lead l8 through switch 38. Since the wire 23 of the transformer and relay energizing circuit is connected to the lead I! through the safetv switch IS. the opening or lock-out of the switch It results in complete disabling of the burner system.

The lock-out switch I! as herein shown comprises a yicldable stationary contact 3'1 and a movable contact 3| carried by a pivoted arm 32 which is normally urged toward a switch-o ening position by means such as a spring 33. and when the switch i8 is opened. it is locked in its open or safety lock-out position by a latch 34. The latch 34 comprises an arm pivoted at 35 and normallyheld against the end of the switch arm 32 by means such as a spring 33, so that wh n the switch arm 32 shifts sufilcienly away from its switch-closing position, the latch 34 is shifted to an active blocking position, shown in do ted lines in the drawing. in which it acts to latch the safety switch It in its open or lock-out position. When this lock-out condition arises, the burner motor and the control system are eilectively disabled, and no further fuel may be fed into the combustion chamber until the latch 34 has been released and switch arm 32 again shifted to switch-closing position.

For use in restoring the safety switch It to its closed position, a. shiftable restoring or re-set member :1 is provided; The member 3 in a re-setting operation, first acts upon the .atch member 34 to release the same, and in further movement engages the switch arm 32 to move the arm 32 against the force of is spring 33 to its switch-closing position. Preferably a normally closed re-set switch 38 is provided between the line voltage lead It and the contact 33 of the lock-out switch, and the re-set member 31 is arranged to open the re-set switch 33 whenever the re-set lever is actuated to re-set or close the lock-out switch It. The re-set switch 33 is allowed to close only when the re-set member 31 is released.

In accordance with the present invention, the safety switch It is maintained in its closed position by a series of shiftable mechanical abutment devices which in normal burner starting, running and stopping operations are shifted in a predetermined normal sequence such that at least one of the abutments is'eflective at all times to maintain the safety switch It closed, and when abnormal combustion conditions arise, are shifted in a different sequence such that the safety switch it is released for movement to its lock-out or open position.

The abutment devices which" cooperate in maintaining the safety switch It closed during normal combustion conditions, are associated with and operated by the relay 2|, a timer mechanism 40 which determines the length of the burner starting period, and a combustion responsive means 4| which is responsive to combustion conditions at all times.

The governing action of the relay 2| on the switch I6 is obtained through an abutment 42 carried by the shiftable armature 43 of the relay 2|, the armature 43 being urged by means such as a spring 44 toward its open position as shown in Fig. 1, wherein the projecting abutment 42 engages the switch arm 32 of the safety switch to urge the same toward its switch-closing position. It will be evident, of course, that if the switch arm 32 is in its open or lock-out position, the relay armature 43, while applying yielding switch-closing force to the switch It. will be ineffective to close the switch Hi until the re-set member 31 has been actuated t release the latch 34. It will also be evident that when the relay 2| is energized, the armature 43 is actuated to close the burner. switch 20, and the abutment 42 is withdrawn from its switchclosing or switch-governing relation to the lever 32 of the safety switch. The switch it is then maintained closed by a timer abutment 45 carried and controlled by the timer mechanism 40. The timer mechanism 40 as herein shown is of the compensated thermal type and Comprises a bimetal structure 46 pivoted at its midpoint on a pivot pin 41 and carrying the abutment 45 on one side of its upper end. The bimetal structure 46 preferably comprises upper and lower bimetal elements 45' and 46", reversely related or positioned, as indicated by the arrows, and connected at the midpoint of the structure 44. Preferably, a heat insulating member 41' is interposed between the upper and lower portions of the structure 46. By reason of its central pivotal mounting and the reversed relation of its upper and lower portions, the bimetal structure 46 compensates for changes in ambient temper ature. Opposite the other side of the lower end portion 46" of the bimetal structure" an abutment 48 is provided for engagement by the lower bimetal 46", and the lower bimetal 46" is so disposed that when it is heated, this lower end tends to bow or move to the right as indicated by the arrow. Such bowing of the lower bimetal portion 46" tends to causeclockwise rotation of the bimetal structure 46, about its pivot 41, which shifts the upper end 46' to the right. Adjacent the upper end of the upper bimetal portion 45' a restraining means such as a ma net 49 is provided .which tends to prevent such movement of the upper end toward the right, the magnet 49 thereby tending to maintain the timer abutment 45 in its operative engagement with the switch lever 62. Upon changes in ambient temperature, the opposite bowing of the upper and lower portions 46' and 46" produces the desired compensating action.

when one of the portions- 46' or 46" of the bimetal structure is heated as by means of an electric resistance heater 55, a bowing or warping action results in the heated portion in the general manner above described. With the two bimetal portions 46' and 46" disposed as herein shown, the heater 55 is arranged to heat the lower portion 46",- so that the portion 46" constitutes the active portion of the structure 46. If the portions 46' and 46" were reversed it is to be understood that the heater 56 would be arranged to act on the upper section of the bimetal structure. When the lower portion 46" is heated by the heater 55, it warps. its free lower end toward the right, and since the upper end of the bimetal portion 46' is restrained in its-left hand position by the magnet 49, the lower end of the lower bimetal porton 46" is shifted to the right against the fixed abutment 46. As such heating continues a resilient force is built up in the bimetal portion 46" which at the end of a predetermined burner starting period. as for example 90 seconds, exceeds the restraining force of the magnet thereby causing the upper portion 46' of the bimetal structure 46 to snap away from the magnet and to a right hand or inactive position.

.When the thermostat i4 initially calls for heat. it provides an initial or starting circuitfor the heater 56 extending from one side or terminal of the thermostat i4 through w res 5| and 52 to one end-of the heater 56, while a wire 53 in series connects the other end of the heater to the lower end of the upper bimetal portion 46. At this time the upper end of the timer bimetal structure 46 is normally in its cold or left hand position so that this in tial or starting circuit is extended from the upper bimetal portion 48' to a stationary starting contact 54 which is then engaged by a contact 55 carried by the upper b metal portion 46', and wires 56 and 51 extend in series from the contact 54 to one end of the transformer secondary 21. The other end of the secondary 21 is connected by a wire 58 to the other side or term nal of the thermostat M. This starting circuit is overned by the thermostat l4, and is closed 'hen the thermostat calls for heat. Closure of the startg circuit by the thermostat serves to energ ze the relay 2|, and when thus energ zed the relav closes a relay switch 59. Closure of this switch 59 establishes a new circuit through secondary 21 as follows, transformer secondary 21, wire 56, thermostat l4, wires 5| and 52, heater 56, wire 59', switch 59, and wire 59" to secondary 21.

The switch 59 therefore energizes under the control of the thermostat when contacts 5455 are separated.

When the bimetal structure 46 snaps its upper end away from its left hand position to its right another timing operation.

hand positiomthereby denoting the end of the timed burner starting period, the heater 50 is deenergized so that during burner operation the timer may cool and thereby be conditioned for This end is preferably attained by providing a shunt circuit around the heater 59, as by means of a wire 60 extending from the wire 5| to a stationary contact 6|, the contact 6| being engaged, when the upper end of the bimetal structure is in its right hand position, by a contact 62 carried on the right hand side of the bimetal portion'46'. Thus a shunt circuit is provided around the heater, 56 from the wire 5| through wire 66, contacts 6|-62, the bimetal portion 46', wire 56, wire 59', switch 59, wire 59", secondary 21 and wire 56 to thermostat 4.

It will be understood that the positioning of the contacts 55 and 62 is herein shown schematically, and that to attain best results in practice, these contacts are mounted directly opposite or on the center line of the magnet 49. Moreover, where the upper and lower bimetal portions 46' and 46" have the same deflection characteristics, the contacts 55 and 62 are positioned at a distance above the pivot 41 which corresponds to the distance of the abutment below the pivot 41. This proportioning insures accuracy of compensation for ambient temperature.

In order to prevent the timer from snapping back to its cold position due to the heater 56 being deenergized, and thus maintaining the heater deenergized, means is provided for maintaining the timer in its right hand or inactive position during continuance of burner operation. In the embodiment disclosed in Fig. 1 of the drawing, this end is attained by latch means, such as an arcuately shaped latch member 65 pivoted intermediate its ends at and having one relatively long end. 61 thereof weighted so as to tend by gravity to assume a restraining or latching position wherein it blocks return movement of vthe upper end of the timer bimetal structure 46 from its right hand or inactive position to its left hand or initial position. When the latch 65 is in its effective position it engages a surface '68 on the upper bimetal portion 46 After the upper end of the timer 46 has been latched in its right hand position, it is held in this inactive position until the relay 2| is de-energized or released, and when the relay armature 43 moves to its released or burner-stopping position, an abutment 69 on the armature 43 engages the other arm or end portion 16 of the latch 65 to shift the latch and re,- lease the timer 46 for return movement to its initial or left-hand position. Such return movement is induced by the magnet 49, and iffdesired, the action of the magnet 49 may be augmented by a relatively light spring 1| acting on the lower bimetal portion 46" to induce counterclockwise movement thereof.

In a normal burner starting operation, the ignition means l3 and the burner motor are energized by closure of the relay switch 20, and combustion is normally produced within the timed burner starting period. The heat resulting from such combustion is sensed by the combustion responsive means 4|. This combustion responsive means may be of many different forms but is preferably of the form illustrated and claimed in the co-pending application of Willian Christiansen, Serial No. 236,818, filed October 24, 1938. In the aforementioned Christiansen application a thermally responsive actuator 4| operates through a slip friction connection 4|" to actuate a pivoted stack arm 12, and in response to the detection of combustion, acts to move the arm 12 from a normal cold position determined by an abutment 13 to a hot position determined by an abutment 14. In accordance with the present invention the stack arm 12 in its hot position (shown in dotted outline) provides or acts as an abutment in the path of the switch arm 32 to maintain the safety switch I! closed so long as continued combustion is sensed by the combus tion responsive means 4|.

Thus it will be apparent that when a burner starting operation results in combustion within the predetermined burner-starting period, the stack arm 12 will move to its left hand or hot position against the switch arm 32 before the timer abutment 45 is withdrawn from its switchclosing relation. The stack arm 12 thereafter acts as the sole means for maintaining the safety switch It closed, it being noted that the latch 65 acts to maintain the timer 4. in its right hand or inactive position so long as the relay 2| remains energized or closed. Hence the switchclosing force applied to the switch arm 32 by the stack arm 12 is applied independently of the timer 40.

In the event that combustion does not result within the predetermined burner-starting period, the shifting of the timer abutment 45 to the right hand position at the end of the starting period results in a release of the switch arm 32, it being observed that due to the absence of combustion, the stack arm I! has remained in its right hand or cold position. This results in a lock-out operation of the safety switch It so that the entire burner system is de-energized and rendered inoperative. When this lock-out action takes place the relay armature 43 is released and tends to move the switch arm 32 of the switch iii to its switch-closing position, but closure of the switch It is prevented due to the latching action of the lock-out latch 34.

During normal burner operation the stack arm 12 'serves as the sole control for the safety switch It, and in the event of a flame failure, the cooling of the combustion responsive means 4| causes the stack arm 12 to be withdrawn to its cold or right hand position. Since the relay 2l is still energized, the relay abutment 42 remains in its inactive position; and the timer is maintained in its inactive position by its latch 65. Hence the withdrawal of the combustion governed abutment I2 results in immediate release of the arm 32 of the safety switchlB and causes a lockout operation.

Since the upper end of the timer 4!) is latched in its right hand or inactive position during normal burner operation, and since the heater 50 is then deenergized, the timer may be said to run cold," and except in the case of unusually short burner operations, is reconditioned during the burner operation for a subsequent timing operation. This is important in case of relatively short power failures, since it produces an immediate restarting or recycling of the burner mechanism.

To insure a starting period of the desired length even when a power failure occurs shortly before completion of a timing operation, means is provided to modify the action of the magnet 48 when the relay is released. To this end an armature 49 is mounted on the relay armature 43 so that it shades the magnet 48 when the relay is released, and is moved away from its shading relation when the relay is closed. Thus, in the event of a power failure Just prior to the c0mpletion of a timing cycle. the restraining force f the magnet 49 is reduced by the shading action of the armature 49' as soon as the relay is released, so that the timer bimetal 48' is released and shifts to the'right. This breaks the starting circuit through contacts 54-", and a subsequent starting operation cannot take place until the timer has cooled sufllciently to close the starting contacts.

With the timer 40 held in its inactive position during continued closure or energization of the relay 2|, the continued closure of the safety switch it is governed solely by the combustion responsive means 4|; and in the event of a dame failure under such normal running conditions,

the withdrawal of the combustion governed abutment 1! releases the safety switch it for immediate lock-out operation. Such lock-out operation takes place independently of the timer 40.

Since the starting circuit can be closed through contacts 54-55 only after the timer bimetal structure 46 has fully cooled, the relatively free action of the timer bimetal structure 46 in the present system assures uniformity in the timing of the burner starting period. This result is attained by reason of the fact that the bimetal structure 48 returns to its initial or normal form and relation solely by reason of its cooling rather than through the application of outside restoring force, Hence the timer bimetal changes its form, or warps back and forth, solely in response to temperature changes in the bimetal, independently of the other elements of the system, such as the relay or the combustion responsive means. The design and calibration of the timer of the present system is therefore simplified, and uniformity of timing operation is rendered independent of variations in design of such other elements.

In Fig. 2 of the drawing an alternative embodiment of the invention is disclosed, and in this alternative embodiment most of the elements and relationships of the circuit and the control elements are the same as in the Fig. 1 embodiment. In the Fig. 2 embodiment, however, the timer U is maintained in its inactive or right hand position by magnetic means, rather than by the latch means 85 of the Fig. 1 embodiment. Thus in the embodiment illustrated in Fig. 2 a magnet is provided on the right hand side of the upper end of the bimetal structure 46 so that when the upper end of the timer bimetal structure 48 is in its right hand or inactive position the upper end thereof is under the restraining influence of the magnet 80. The magnet 80 normally, or during burner operation, exerts suillcient force on the bimetal 46 to maintain the upper end of the timer in its inactive or right hand position, but when the relay 2! is released, it is operable to release the bimetal structure 46 from the restraining influence of the magnet 80 so that the upper bimetal portion 46' may return to its left hand or initial position wherein it is maintained by the influence of the magnet 49.

In the present instance, this release of the bimetal structure 46 from the influence and restraining action of the magnet 80 is attained through the provision of a shading armature II on the relay armature 43, and when the relay is energized or closed the shading armature BI is withdrawn or separated from the magnet 80. When the shading armature BI is thus withdrawn, the magnetic influence of the magnet ll is sumciently strong to retain the bimetal structure I in its inactive position against the force of the spring II and against; the attractive force of the other magnet 48, but when the'relay' is released, and the shading armature 8| is moved into its left hand or shading relation to the magnet II, the restraining force of the magnet ill is so reduced that the bimetal structure It is released and, if cold, returns to its initial position. Thus with the structure illustrated in Fig. 2, the operational characteristics of the system are substantially the same as with the burner system illustrated in Fig. 1; and if desired, provision may be made to cause release of the bimetal structure from its active position in the event of power failure near the end of a timing cycle. Such provision may be-made through the use of another shading armature mounted and functioning in the manner described'with relation to the shading. armature 49' of the embodiment of Fig. 1. It will be understood, of course, that in practice the abutment arms 42 and 45 of Fig. 2 would be so arranged laterally as to avoid interference with each other in their control 'movemtnts, the

present illustration being merely schematic in character.

.While for the purpose of simplicity the invention is illustrated applied to a constant ignition type of control system, it will be understood that it is equally adaptable to systems providing intermittent ignition operation. Such intermittent ignition operation may be obtained in any desired manner. For instance, an ignition switch can be placed in the circuit to the ignition means, 1

such switch being actuated in the same manner as the starting switch 54-55.

From the foregoing description it will be evident that the present invention provides a new I anism having an operating position permitting operation of the burner and a lock-out position in which the burner is prevented from operating, first actuating means for said switch mechanism comprising a timer including an element shifting from an initial position to another position a timedperiod after starting of the burner, said first actuating means being adapted to cause said switch mechanism to assume its operating position when said element is in its initial position while tending to cause said switch mechanism to assume its lock-out position when said element is in said other position, second actuating means including a combustion responsive device for normally preventing movement of said, switch mechanism to its lock-out position when combustion is present while causing movement of said switch mechanism to its lock-out position upon failure of combustion, means conditioning said timer for return of said element to its initial position while the burner is in operation, and means for preventing said timer element from 88 8 its initial position until the burner is placed out of operation.

2. In a burner control system, a switch mechanism having an operating position permitting operation of the burner and a lock-out position in which the burner is Prevented from operating, first actuating means for said switch mechanism comprising a thermo-electri'c timer including an element shifting from an initial position to a final position a timed period after starting of the burner, said first actuating means being adapted to cause said switch mechanism to remain in its operating position when said element is in its initial position while tending to cause said switch mechanism to assume its lock-out position when said element is in said other position, second actuating means including a combustion responsive device for normally preventing movement of said switch mechanism to its lock-out position when, combustion is present while causing movement of said switch mechanism to its lockout position upon failure of combustion, switching means controlled by said thermo-electric timer for conditioning said timer for return of said element to its initial position after said I timed period has expired and during operation of the burner, and means for preventing shifting of said element to its initial position until the burner is placed out of operation.

3. In a burner control system, a condition reponsive device responsive to demand for operation and non-operation of theburner, a relay controlled by said condition responsive device and having a relay element movable from one position to another for starting and stopping the burner, a safety switch mechanism having a normal position permitting operation of the burner under the control of said condition responsive device, said safety switch mechanism also having a lock-out position in which the burner is prevented from operating, first actuating means for said safety switch mechanism comprising a thermo-electric timer including an element shifting from an initial position to another position a timed period after starting of the burner, said first actuating means being adapted to cause said safety switch mechanism to remain in its normal position when said element is in its initial position while tending to cause said safety switch mechanism to assume its lock-out position when said element is in said other position, second actuating means including a combustion responsive device for normally preventing movement of said safety switch mechanism to its lock-out position when combustion is present while causing movement of said safety switch mechanism to its lock-out position upon failure of combustion,

switching means controlled by said thermo-electric timer for conditioning said timer for return of its element to its initial position after the timed periodhas expired and during operation of the burner, latch means for preventing shifting of the timer element to its initial position, and means operated by said relay element upon normal stopping of the burner for releasing said latch means and maintaining said safety switch mechanism ing and running of said burner comprising a timer mechanism having an initial position in which it is operable to apply a switchwlosin'g force to said switch during a timing period and movable to a second position at the end of a predetermined burner-starting period to remove its switch-closing force at the end of said period, latch means operable to latch said timer mech anism in said second position during normal burner operation, a combustion responsive means operable in response to combustion produced within said timing period to apply a simi lar switch closing force to said switch to maintain said switch closed during continuance of such combustion, and means operable to release said timer mechanism from said latch means to condition the timer mechanmm for a subsequent timing operation.

5. An burner system comprising a burner having a starting and running circuit, a safety' switch biased toward open position and included in a dominating controlling relation to said burner starting and running circuit, a relay governed by said circuit, and means for maintaining said switch closed during normal starting and running of the burner comprising a timer mechanism operable to prevent opening of said switch during and to the end of a predetermined burner-starting period and to become ineffective to prevent such opening at the end of said period, a combustion responsive means operable in response to combustion produced within said period to maintain said switch closed after the timer mechanism becomes ineflective, latch means normally urged toward a latching relation with said timer mechanism to latch the timer mechanism in its ineffective position at the end of said timing period, and means operable as an incident to subsequent operation of said relay to release said latch means.

6. An automatic burner system comprising, in combination, a burner having a burner starting and rlmning circuit, a relay included in a goveming relation to said burner starting and run ning circuit and having a burner starting and burner stopping position, a safety lock-out switch constantly biased toward open position and included in dominating controlling relation to such a burner starting and running circuit, a safety lock-out latch operable to latcii said safety switch in its open position, a manual reset member for said safety switch constituting the sole means for releasing said safety latch and returning said safety switch to closed position, a timer operable through a predetermined burner starting period initiated as an incident to the movement of said relay to its burner starting position and having means including a movable abutment element operable during said starting period to maintain said safety switch in its closed position, said abutment element be ing shifted by said timer to an inactive position at the end of said starting period and tending thereafter to return to its initial position, a timer latch operable to latch said abutment element against return to its initial position, a combustion responsive means having means including an abutment element shifted in response to combustion produced during said burner starting period to supersede said timer abutment at the end of the starting period in maintaining said safety switch in closed position, and means operated by said relay as an incident toits movement to its burner stopping position to release an incident aemon said timer latch and restore said timer abutment element to dominating control of said safety switch.

i. A burner system comprising, in combination, a humor having a starting and running control circuit, a relay included in a governing relation to said burner starting and running circuit and having a burner starting and burner stopping position, a safety lock-out switch constantly biased toward open position and included in dominating controlling relation to such a burner starting and running cincuit, a safety lock-out latch operable to latch said safety switch in its open position, a. manual re-set member for said safety switch constituting the sole means for releasing said safety latch and returning said safety switch to closed position, a timer operable through a predetermined burner starting period initiated as an incident to the movement oi said relay to its burner starting position and having means including a movable abutment element opt. erable during said starting period to maintain said safety switch in its closed position, said abutment element being shifted by said timer from an active position to an inactive position at the end of said startin period and tending thereafter to return to its initial position, a timer latch operable to latch sai abutment element against return to its initial position, a combustion responsive means having mean including an abutment element shifted in response to combustion produced during said burner starting period to super. sede said timer abutment at the end of the starting period in maintaining said saiety switch in closed position, means operated by said relay as to its movement to its burner stopping position to release said timer latch an restore said timer abutment element to dominating control of said safety switch, and abutment means operable when said relay moves to its burner stoppin position to urge said switch closed so long as said relay remains in said burner stopping position.

8. An automatic burner system comprising, in combination, a burner having a burner starting and running circuit to control the starting and stopping of a burner, a relay controlling said circuit and having burner starting and burner stopping positions, a combustion responsive means having an abutment element shiftable in response to combustion from a cold position to a hot position, a timer having an abutment element movable at the end of a predetermined timed burner-starting period from an initial position to an inactive position, a safety lock-out switch biased toward open position and included in a dominating controlling relation to such a burner lock-out switch being held against opening by said timer element when in its, initial position and by said abutment element of said combustion responsive means when in said hot position, latch means operable to latch sai timer element in its inactive position after movement to said inactive position, and means actuated by said relay when it returns to its burner stopping position to release said latch means to permit return of said timer element to its initial position wherein the timer element acts to prevent opening of said switch when the combustion responsive element moves to its cold position.

9. In an electrically controlled burner system having a burner and electrically operated means for initiating and terminating operation of the starting and running circuit, said safety completion of a timing able abutment elements each having an active,

position and an inactive position, and either of said abutment elements in its active position being operatively associated with said safety switch to maintain the same closed, a thermal timer operatively connected to one of said abutments to maintain the same in its active switch closing position during and to the end of a predetermined burner starting period and thereafter to shift its abutment to its inactive position, a heater for said timer energized by said control circuit and governed by said control thermostat to initiate operation of said timer, means operable upon said control circuit to de-energize said heater when the timer abutment is in its inactive position, combustion responsive means operatively connected to the other of said abutment elements and operable in the absence of combustion to maintain its abutment element in its inactive position and in the presence of combustion to shift its element to itsactive switch closing position, and means operable during continued operation of the burner to maintain said timer abutment element in its inactive position, said starting switch being maintained open by said timer until said timer has returned to its initial position.

10. An automatic burner system comprising, in combination, a burner, a burner starting and running circuit to control the starting and stopping of the burner, a relay controlling said circuit and having burner starting and burner stopping positions, a heater actuated thermostatic timer having means operable to impart a snap action thereto from an initial position to an inactive position at the end of its timing period and having means operable to compensate for ambient temperature, a control circuit for said relay and an energizing circuit for the heater of said timer both adapted for control by a room thermostat, means operable to disable said heater when said timer is in its inactive position, a safety lock-out switch biased toward open position and included in a dominating controlling relation to said burner starting and running circuit, means operatively connected to said timer and operable when said timer is in its initial position to hold said safety switch closed and to release said safety switch for opening movement when said timer is in its inactive position, a combustion responsive means having an element shiftable in response to combustion from an inactive cold position to a hot position wherein it acts to hold said safety switch closed, latch means operable to latch said timer in its inactive position after completion of a timing movement whereby, duringcontinued burner operation, continued closure of said safety switch is rendered dependent solely upon continuance of combustion, and means actuated by said relay when it.

returns to its burner stopping position to release said latch means to permit return of said timer element to its initial position wherein the timer acts to prevent opening of said switch when the combustion responsive element moves to its cold position,

11. An automatic burner system comprising, in combination, a burner having a burner starting and running circuit to control the starting and stoppingof the burner, a relay controlling said circuit and having burner startlngand burner stopping pcsitions, a heater actuated thermostatic timer movable in a timing operation thereof from an initial position to an inactive'position, a control circuit for said relay and an energizing circuit for the heater of said timer both adapted for control by a room thermostat, means operable to disable said heater when said timer is in its lnactiveposition, a safety lock-out switch biased toward open position and included in a dominating controlling relation to such a burner,

starting and running circuit, means including an abutment face operatively connected to said timer and operable when said timer is in its initial position to hold said safety switch closed and to release said safety switch for opening movement when said timer is in its inactive position,

a combustion responsive means having an abutment element shiftablein response to combustion from an inactive cold position to a hot position wherein it acts to hold said safety switch closed after release of said switch by said timer, holding means operable to hold said timer in its inactive position after completion of a timing movement whereby, during continued normal o burner operation, continued closure of said safety switch is rendered dependent solely upon continuance of combustion, and means actuated by said relay when it returns to its burner stopping position to release said holding means to permit return of said timerelement to its initial position wherein the timer acts to prevent opening of said switch when the combustion responsive element moves to its cold position. a

12. An automatic burner system comprising, in combination, a burner having a burner starting and running circuit to control the starting and stopping of a burner, the relay controlling said circuit and having burner starting and burner stopping positions, a combustion responsive means having an abutment element shiftable in response to combustion from a cold position to a hot position, a thermal timer having an abutmcnt element movable at the end of a predetermined timed burner-starting period from an initial position to an inactive position, asafety lock out switch biased toward open position and included in a dominating controlling relation to such a burnerstarting and running circuit, said safety lock-out switch being held against opening by said timer element when in its initial position and by said abutment element of said combustion responsive means when in said hot position, restraining means operable to restrain said timer element in its inactive position after completion of a timing movement to said inactive position, means actuated by said relay when it returns to its burner stopping position to release saidrestraining means to permit return of said timer element to its initial position wherein the 55 timer element acts toprevent opening of said. switch when the combustion responsive element moves to its cold position, an energizing circuit for said relay including a starting switch con trolled by said timer element to open when said timer moves out of its initial position, a heater for said timer energized when said relay is energized and de-energized when said timer moves to said inactive position, and means operable in the event of a momentary power failure near the end of a timingperiod to cause movement of said timer from its initial position whereby to open said starting switch a d thereby insure adequate cooling of said timer before initiation of another timing opera-tion thereof.

13. In a fuel burning heating system a fuel burner including an operating motor and an energizlng circuit therefor, a relay controlling said circuit and having burner starting and burner stopping positions, a combustion responsive means having an abutment shiftable in response to combustion from a cold position to a hot position, a thermal timer having an abutment movable at the end of a predetermined timed burner-starting period from an active position to an inactive position, an electric heater for said timer having a control circuit operable to de-energize said heater when said abutment is in its inactive position, a safety lock-out switch biased toward open position and included in -'a dominating controlling relation to such a burner starting and running circuit, a shiftable latch member operable to latch said lock-out switch in its lock-out position, said timer abutment being operable when in its active position to hold said switch in its closed position, magnetic means operable upon said timer to hold said timer abutment in said inactive position, and the other abutment being operable when in its hot position to hold said switch in its closed position, and being operable in its cold position to release said switch for movement to its open position, and shading means operable by said relay as it is returned to its burner stopping position for reducing the effect of said magnetic means.

14. In an electric control system for fuel burn ers, in combination with electrically operated means for initiating and maintaining combustion, a circuit therefor controlled by a room thermostat, safety lock-out means comprising switch means urged toward open position and arranged when in open position to render said electrically operated means ineffective, said switch means including a safety latch operable to latch said switch means in its open position, timer means and combustion responsive means operable in a normal burner starting operation to maintain said switch means closed and means operable as an incident to the termination of burner operation to apply a yielding force to said switch means for holding said switch means closed independently of said timer means and combustion responsive means.

15. In a control system for a fuel burner, the combination of, a condition responsive device responsive to the demand for operation and nonoperation of the burner, a relay controlled by said condition responsive device and having a relay element movable from one position to another for starting and stopping the burner, a safety switch mechanism having a normal position permitting operation of the burner under the control of the condition responsive device, said safety switch mechanism also having a lock-out position in which the burner is prevented from operating, biasing means for urging said safety switch mechanism from its normal position to its lock-out position, timer means controlled by said condition responsive device and having an initial position and a second position, said timer means moving from its initial position to its second position a period of time after starting of the burner, a combustion responsive device having a cold position and a hot position, said combustion responsive device moving from its cold position to its hot position upon occurrence of combustion, means for preventing movement of said safety switch mechanism to its lock-out position when either the timer means is in its initial position or the combustion responsive means is in its hot position, and means actuated upon said relay moving to burner stopping position for applying a force to said safety switch mechanism which opposes said biasing means for preventing movement of said safety switch mechanism to it lock-out position irrespective of said timer means or said combustion responsive mechanism.

16. In a control system for a fuel burner, the combination of, a condition responsive device responsive to the demand for operation and nonoperation of the burner, a relay controlled by said condition responsive device and having a relay element movable from one position to another for starting and stopping the burner, a safety switch mechanism having a normal position permitting operation of the burner under the control of the condition responsive device, said safety switch mechanism also having a lock-out position in which the burner is prevented from operating, biasing means for urging said safety switch mechanism from its normal position to its lock-out position, timer means controlled by said condition responsive device and having an initial position and a second position, said timer means moving from its initial position to its second position a period of time after starting of the burner, means actuated upon movement of said timer means to its initial position for applying a force to said safety switch mechanism which opposes said biasing means for preventing movement of said safety switch mechanism to its lock-out position, a combustion responsive device having a cold position and a hot position, said combustion responsive device moving from its cold position to its hot position upon occurrence of combustion, means actuated upon movement of said combustion responsive device to its hot position for applying an opposing force to the safety switch mechanism to prevent movement thereof to its lock-out position, and means actuated upon movement of the relay to burner stopping position for applying an opposing force to the safety switch mechanism for preventing movement thereof to lock-out position irrespective of said timer means or said combustion responsive device.

17. In a burner control system, the combination of, a switch mechanism having a first position permitting operation of the burner and a second position in which the burner is prevented from operating under all circumstances, a condition responsive device responsive to the de-' mand for operation and non-operation of the burner for starting and stopping the same, a thermoelectric timer having a thermostatic element and a heater, said heater being controlled by said condition responsive device and said thermostatic element tending to cause movement of said switch mechanism from one position to another as said thermostatic element moves under the influence of said heater, means actuated by the thermostatic element after movement thereof for controlling said heater in a manner to cause return movement of said thermostatic element, and means controlled by said condition responsive device for preventing such return movement of said thermostatic element.

18. In a burner control system, the combination of, a switch mechanism having a first position permitting operation of the burner and a second position in which the burner is prevented from operating under all circumstances, a condition responsive device responsive to the demand for operation and. non-operation of the burner for starting and stopping the same, a thermoelectric timer having a thermostatic element and a heater, said heater being energized by said condition responsive device upon demand for operation of the burner and causing movement of said thermostatic element in a direction tending to cause movement of the switch mechanism from its first position to its second position a period of time after the burner is started, combustion responsive stop means operative upon presence of combustion to prevent such movement of the switch mechanism, means actuated by the thermostatic element after movement thereof for controlling said heater in a manner to cause return movement of the thermostatic element, and means controlled by the condition responsive device for preventing such return movement of the thermostatic element.

19. In a burnercontrol system, the combination oi. a switch mechanism having a first position permitting operation of the burner and a second position in which the burner is prevented from operating under all circumstances, a condition responsive device responsive to the demand for operation and non-operation o! the burner for 7 starting andstopping the same, a thermoelectric timer having a thermostatic element and electric heating means, said heating means bein controlled by said condition responsive device and said thermostatic element tending to cause movement oi. said switch mechanism from one position to another as said thermostatic element moves under the influence of said heating means.

- .ms'rm A. DEUBEL. 

